Converting an iterator over statements to ntriples

[D063520]

Hi,

I have an iterator over statements:

Statement st = statements.next();
String ntriple = ......

And I would like to get back a string that contains the Ntriple representation of the statement st.

Can someone help me out?

[frensjan]

Iterator<Statement> statements = ...;

StringWriter sw = new StringWriter();
RDFWriter writer = Rio.createWriter(RDFFormat.NTRIPLES, sw);
writer.startRDF();
statements.forEachRemaining(writer::handleStatement);
writer.endRDF();
String ntriples = sw.toString();

This would give you a string with all the statements from the iterator. If you must have a string per statement, you would probably need to create a writer per statement then.

Iterator<Statement> statements = ...;

while (statements.hasNext()) {
    StringWriter sw = new StringWriter();
    RDFWriter writer = Rio.createWriter(RDFFormat.NTRIPLES, sw);
    writer.startRDF();
    writer.handleStatement(statements.next());
    writer.endRDF();
    String ntriple = sw.toString();
}

[D063520]

thank you!

[barthanssens]

Excellent answer from @frensjan

FWIW, there is also a NTriplesUtil class that might be useful (https://rdf4j.org/javadoc/4.2.2/org/eclipse/rdf4j/rio/helpers/NTriplesUtil.html) in this specific case.
And if the Statements originate from a Model / Iterable<Statement>, there is possible shortcut in using Rio.write(model, out, RDFFormat.NTRIPLES)

[D063520]

thank you!